It is desirable to be able to separate selected materials from fluids, including gases such as air, and liquids such as water. It is known that particles may be removed by physical processes, such as passing the fluid through filters, sieves, or other structures which will catch the particles while allowing the fluid medium to pass. Thus, for example, dust may be removed from the air, silt from water, etc. It is also known that certain materials such as metals, ions and/or colloids, may be removed from fluids by exposing them to surfaces which have an ionic bias, i.e. are either anionically or cationically charged so as to attract, hold, and thereby separate out from the fluid medium materials of opposite ionic bias. In this manner, for example, metals may be extracted from seawater. It is known also that the surface so ionically biased may be in the form of an endless, woven belt moved relative to the fluid medium in question. By this means, the subsequent steps of removing the extracted material and re-establishing the ionic bias of the belt may be facilitated. In this connection, reference is made to U.S. Pat. Nos. 2,678,132; 3,062,379; and 3,436,213.
One of the areas of technical interest which has recently received new interest is that of pollution abatement. Thus, for example, industrial effluents are increasingly being monitored with a view to extracting therefrom materials which contaminate the environment. Although the relatively large particles of such contaminants may be removed with relative ease and low cost, the smaller particles and suspended materials are difficult, and costly, to remove.
Accordingly, it is an object of the present invention to provide methods by which selected materials may be removed from fluid media which are technically reliable, efficient, and effective, and may be economically constructed and operated.